The present invention relates to a method of establishing clam bed colonies by a captive-reared clam releasing program, and mobile floating hatchery for facilitating the implementation of the method and which is usable, as well, for spawning other aquatic species of shellfish and finfish.
Attempts over the last 20 years to increase the population of clams have not heretofore proved to yield impressive results. For example, there are significantly reduced numbers of clams (specie Mercenaria mercenaria) remaining harvestable in the bays and harbors of Long Island, N.Y., and no doubt other such similar beds around the world are greatly depleted.
In accordance with the current state of the art, the clam sperm, egg & subsequent larvae are handled in a clinical laboratory setting, yielding less that satisfying results. Micro-screening techniques are employed in the laboratory, and the larvae are filtered 3 or 4 times before their next stage of development following the larval state.
In the lab, scientists have been guilty not only of exposing the clam larvae to torturous unnatural screenings (exposed to air and UV light), but also of depriving the clams a sandy bottom for them to “set” in. “Setting” is the term used to describe the process implemented by the clam in a natural environment when adapting to the sea or bay bottom. For this reason, the lab-generated clams have not been exposed to the natural conditions existing in the bays during their early development, and therefore, do not acclimate to the natural environment as would naturally occurring juvenile clams. When they are finally released, they have been observed to sit atop of the sand bed, and are therefore easy prey to their natural enemies because they do not possess or exhibit the behavioral traits necessary for survival.
Sometimes, in accordance with conventional practice, scientists even use epinephrine (Adrenaline) to stimulate the clams into setting. But the fact remains, that such scientific endeavors have failed to provide an adequate method of repopulating clam beds.
In addition to land-based hatcheries which produce clams in captivity as outlined above, floating hatcheries are also presently known in the art, and which are generally moored in a fixed position. As such, they are not provided with propellers or other form of mobility. Moreover, they are generally operated as an open system, allowing seawater to enter the holding areas in which the clams are located, in order to provide food in the form of algae and plankton for the growing clams. Such system may expose the clams to predator organisms, parasitic attack and/or other contamination.
In accordance with the above described hatchery procedures (both laboratory, i.e., land-based, and floating) the clams are raised until they can be sold as “seed,” at which time they are generally about the size of a pinky nail. At this advanced size, as mentioned above, they do not exhibit an effective degree of burrowing when released.
Accordingly, it is an object of the invention to provide a clam spawning and seeding program which overcomes the drawbacks of the prior art.
It is a further object of the invention to a floating hatchery which promotes such spawning and a seeding program and which is useful for spawning other shellfish and finfish.